1
|
Fu H, Rong J, Chen Z, Zhou J, Collier T, Liang SH. Positron Emission Tomography (PET) Imaging Tracers for Serotonin Receptors. J Med Chem 2022; 65:10755-10808. [PMID: 35939391 DOI: 10.1021/acs.jmedchem.2c00633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) and 5-HT receptors (5-HTRs) have crucial roles in various neuropsychiatric disorders and neurodegenerative diseases, making them attractive diagnostic and therapeutic targets. Positron emission tomography (PET) is a noninvasive nuclear molecular imaging technique and is an essential tool in clinical diagnosis and drug discovery. In this context, numerous PET ligands have been developed for "visualizing" 5-HTRs in the brain and translated into human use to study disease mechanisms and/or support drug development. Herein, we present a comprehensive repertoire of 5-HTR PET ligands by focusing on their chemotypes and performance in PET imaging studies. Furthermore, this Perspective summarizes recent 5-HTR-focused drug discovery, including biased agonists and allosteric modulators, which would stimulate the development of more potent and subtype-selective 5-HTR PET ligands and thus further our understanding of 5-HTR biology.
Collapse
Affiliation(s)
- Hualong Fu
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Jian Rong
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Zhen Chen
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, College of Chemical Engineering, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
| | - Jingyin Zhou
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Thomas Collier
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| |
Collapse
|
2
|
In vitro permeability, pharmacokinetics and brain uptake of WAY-100635 and FCWAY in rats using liquid chromatography electrospray ionization tandem mass spectrometry. Arch Pharm Res 2014; 38:1072-9. [PMID: 24838378 DOI: 10.1007/s12272-014-0369-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Accepted: 03/13/2014] [Indexed: 01/16/2023]
Abstract
Positron emission tomography (PET) is a sensitive non-invasive imaging technique. To reduce imaging measurements of defects, there is a demand for proper LC-ESI-MS/MS method to carry out with its specificity and sensitivity. This study describes a rapid and simple liquid chromatography electrospray ionization tandem-MS/MS (LC-ESI-MS/MS) method for determination of both PET tracers: N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridyl)cyclohexanecarboxamide (WAY-100635) and 4-fluoro-N-[2-[4-(2-methoxylphenyl)-1-piperazino]ethyl]-N-(2-pyridyl)cyclohexanecarboxamide (FCWAY). Both target compounds were prepared by one-step protein precipitation with acetonitrile and methanol (1:1, v/v), and analyzed using a C18 column. This simple method has an excellent linearity, selectivity and sensitivity. Precision and accuracy values for the intra-day and inter-day validation were below 12%. The limit of quantification (LOQ) for both target compounds was defined as 1 ng/mL in plasma and 5 ng/mL in brain homogenate. The stability of both compounds is considered stable under a various experimental conditions. The in vitro MDR-MDCK cell permeability showed the both compounds have high permeability (Papp, A→B ≥ 20 × 10(-6 )cm/s) and low efflux ratio (≤2.0). Brain to blood (AUCbrain/AUCblood) distribution ratios in rats were 3.15 ± 0.42 for WAY-100635 and 2.20 ± 0.34 for FCWAY, respectively, and these results suggest that LC-ESI-MS/MS method might be a supplementary way for the identifying and understanding of radiopharmaceuticals.
Collapse
|
3
|
Nics L, Hahn A, Zeilinger M, Vraka C, Ungersboeck J, Haeusler D, Hartmann S, Wagner KH, Lanzenberger R, Wadsak W, Mitterhauser M. Quantification of the radio-metabolites of the serotonin-1A receptor radioligand [carbonyl-11C]WAY-100635 in human plasma: An HPLC-assay which enables measurement of two patients in parallel. Appl Radiat Isot 2012; 70:2730-6. [DOI: 10.1016/j.apradiso.2012.08.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Revised: 08/30/2012] [Accepted: 08/30/2012] [Indexed: 10/27/2022]
|
4
|
Ma Y, Kiesewetter DO, Lang L, Gu D, Chen X. Applications of LC-MS in PET radioligand development and metabolic elucidation. Curr Drug Metab 2011; 11:483-93. [PMID: 20540692 DOI: 10.2174/138920010791636167] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Accepted: 05/11/2010] [Indexed: 11/22/2022]
Abstract
Positron emission tomography (PET) is a very sensitive molecular imaging technique that when employed with an appropriate radioligand has the ability to quantititate physiological processes in a non-invasive manner. Since the imaging technique detects all radioactive emissions in the field of view, the presence and biological activity of radiolabeled metabolites must be determined for each radioligand in order to validate the utility of the radiotracer for measuring the desired physiological process. Thus, the identification of metabolic profiles of radiolabeled compounds is an important aspect of design, development, and validation of new radiopharmaceuticals and their applications in drug development and molecular imaging. Metabolite identification for different chemical classes of radiopharmaceuticals allows rational design to minimize the formation and accumulation of metabolites in the target tissue, either through enhanced excretion or minimized metabolism. This review will discuss methods for identifying and quantitating metabolites during the pre-clinical development of radiopharmaceuticals with special emphasis on the application of LC/MS.
Collapse
Affiliation(s)
- Ying Ma
- Laboratory of Molecular Imaging and Nanomedicine (LOMIN), National Institute of Biomedical Imaging and Bioengineering (NIBIB), National Institutes of health (NIH), Bethesda, MD 20892, USA
| | | | | | | | | |
Collapse
|
5
|
Spinelli S, Chefer S, Carson RE, Jagoda E, Lang L, Heilig M, Barr CS, Suomi SJ, Higley JD, Stein EA. Effects of early-life stress on serotonin(1A) receptors in juvenile Rhesus monkeys measured by positron emission tomography. Biol Psychiatry 2010; 67:1146-53. [PMID: 20172506 PMCID: PMC2882499 DOI: 10.1016/j.biopsych.2009.12.030] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Revised: 12/14/2009] [Accepted: 12/26/2009] [Indexed: 12/01/2022]
Abstract
BACKGROUND Traumatic experiences in early childhood are associated with increased risk for developing mood and anxiety disorders later in life. Low serotonin(1A) receptor (5-HT(1A)R) density during development has been proposed as a trait-like characteristic leading to increased vulnerability of stress-related neuropsychiatric disorders. METHODS To assess the relationship between early-life stress and alterations in the serotonin system during development, we used positron emission tomography to measure in vivo 5-HT(1A)R density and apparent dissociation constant (K(D)(app)) in the brain of juvenile Rhesus monkeys exposed to the early-life stress of peer-rearing. RESULTS In general, 5-HT(1A)R density and K(D)(app) were decreased in peer-reared compared with control mother-reared animals. However, increase in receptor density was found in the dorsomedial prefrontal cortex of peer-reared females. CONCLUSIONS These findings suggest that exposure to an adverse early-life environment during infancy is associated with long-term alterations in the serotonin system and support previous studies suggesting that reduced 5-HT(1A)R density during development might be a factor increasing vulnerability to stress-related neuropsychiatric disorders. Furthermore, alterations in the serotonin system seemed to be gender- and region-specific, providing a biological basis for the higher prevalence of affective disorders in women.
Collapse
Affiliation(s)
- Simona Spinelli
- National Institute on Alcohol Abuse and Alcoholism, Poolesville, MD, USA.
| | - Svetlana Chefer
- Neuroimaging Research Branch, National Institute on Drug Abuse, Baltimore, MD
| | | | - Elaine Jagoda
- National Institute of Biomedical Imaging and Bioengineering, Bethesda, MD
| | - Lixin Lang
- National Institute of Biomedical Imaging and Bioengineering, Bethesda, MD
| | - Markus Heilig
- National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD
| | - Christina S. Barr
- Laboratory of Clinical and Translational Studies, National Institute on Alcohol Abuse and Alcoholism, Poolesville, MD
| | - Stephen J. Suomi
- Laboratory of Comparative Ethology, National Institute of Child Health and Human Development, Poolesville, MD
| | - J. Dee Higley
- Department of Psychology, Brigham Young University, Provo, UT
| | - Elliot A. Stein
- Neuroimaging Research Branch, National Institute on Drug Abuse, Baltimore, MD
| |
Collapse
|
6
|
Shetty HU, Zoghbi SS, Siméon FG, Liow JS, Brown AK, Kannan P, Innis RB, Pike VW. Radiodefluorination of 3-fluoro-5-(2-(2-[18F](fluoromethyl)-thiazol-4-yl)ethynyl)benzonitrile ([18F]SP203), a radioligand for imaging brain metabotropic glutamate subtype-5 receptors with positron emission tomography, occurs by glutathionylation in rat brain. J Pharmacol Exp Ther 2008; 327:727-35. [PMID: 18806125 DOI: 10.1124/jpet.108.143347] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Metabotropic glutamate subtype-5 receptors (mGluR5) are implicated in several neuropsychiatric disorders. Positron emission tomography (PET) with a suitable radioligand may enable monitoring of regional brain mGluR5 density before and during treatments. We have developed a new radioligand, 3-fluoro-5-(2-(2-[(18)F](fluoromethyl)thiazol-4-yl)ethynyl)benzonitrile ([(18)F]SP203), for imaging brain mGluR5 in monkey and human. In monkey, radioactivity was observed in bone, showing release of [(18)F]-fluoride ion from [(18)F]SP203. This defluorination was not inhibited by disulfiram, a potent inhibitor of CYP2E1. PET confirmed bone uptake of radioactivity and therefore defluorination of [(18)F]SP203 in rats. To understand the biochemical basis for defluorination, we administered [(18)F]SP203 plus SP203 in rats for ex vivo analysis of metabolites. Radio-high-performance liquid chromatography detected [(18)F]fluoride ion as a major radiometabolite in both brain extract and urine. Incubation of [(18)F]SP203 with brain homogenate also generated this radiometabolite, whereas no metabolism was detected in whole blood in vitro. Liquid chromatography-mass spectrometry analysis of the brain extract detected m/z 548 and 404 ions, assignable to the [M + H](+) of S-glutathione (SP203Glu) and N-acetyl-S-l-cysteine (SP203Nac) conjugates of SP203, respectively. In urine, only the [M + H](+) of SP203Nac was detected. Mass spectrometry/mass spectrometry and multi-stage mass spectrometry analyses of each metabolite yielded product ions consistent with its proposed structure, including the former fluoromethyl group as the site of conjugation. Metabolite structures were confirmed by similar analyses of SP203Glu and SP203Nac, prepared by glutathione S-transferase reaction and chemical synthesis, respectively. Thus, glutathionylation at the 2-fluoromethyl group is responsible for the radiodefluorination of [(18)F]SP203 in rat. This study provides the first demonstration of glutathione-promoted radiodefluorination of a PET radioligand.
Collapse
Affiliation(s)
- H Umesha Shetty
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892-1003, USA.
| | | | | | | | | | | | | | | |
Collapse
|
7
|
Ma Y, Lang L, Kiesewetter D, Jagoda E, Eckelman WC. Species differences in metabolites of PET ligands: serotonergic 5-HT1A receptor antagonists 3-trans-FCWAY and 3-cis-FCWAY. Nucl Med Biol 2006; 33:1013-9. [PMID: 17127175 DOI: 10.1016/j.nucmedbio.2006.09.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2006] [Revised: 09/28/2006] [Accepted: 09/28/2006] [Indexed: 11/25/2022]
Abstract
Liquid chromatography/mass spectrometry (LC/MS), combined with commercially available hepatocytes, has become an indispensable tool in evaluating the presence of these metabolites in target tissues, especially in the brain. Results from in vitro metabolism studies using hepatocytes from different species can demonstrate species differences. Using these techniques, we evaluated the metabolic profile of 3-cis-FCWAY and 3-trans-FCWAY in rat, monkey and human hepatocytes. Hepatocytes were used to produce metabolites in vitro, and liquid chromatography/tandem mass spectrometry was used to identify these metabolites. We found that the metabolic profiles of rat, monkey and human hepatocytes differ dramatically. In rats, aromatic ring oxidation was the major metabolic pathway for both 3-cis-FCWAY and 3-trans-FCWAY; 3-trans-FCWAY had more metabolites (cyclohexane ring oxidation) than 3-cis-FCWAY. In humans, hydrolysis of amide linkage was the major metabolic pathway. In monkeys, both pathways (oxidation and amide hydrolysis) were found in the metabolites. We also found that 3-cis-FCWAY had the slowest defluorination of FCWAY analogues in all species.
Collapse
Affiliation(s)
- Ying Ma
- PET Radiochemistry Group, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892, USA
| | | | | | | | | |
Collapse
|
8
|
Lavén M, Itsenko O, Markides K, Långström B. Determination of metabolic stability of positron emission tomography tracers by LC–MS/MS: An example in WAY-100635 and two analogues. J Pharm Biomed Anal 2006; 40:943-51. [PMID: 16388927 DOI: 10.1016/j.jpba.2005.08.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2004] [Revised: 08/05/2005] [Accepted: 08/06/2005] [Indexed: 10/25/2022]
Abstract
A method is presented for determination of microsomal metabolic stability of potential positron emission tomography (PET) tracers by LC-MS/MS in the lower nm range. The PET tracers used for the study were the serotonin receptor antagonist WAY-100635 and two potential tracer analogues. The sensitivity permitted the substrates to be directly collected from PET radiolabelling batches, containing very low amounts of substance (0.3-7 microg), for subsequent metabolic stability incubations. Sample preparation was minimal, with addition of internal standard, acetonitrile and a fast centrifugation step, as a result of the low protein concentration of the microsome solutions. Linearity (R2 > or = 0.99), precision (inter-assay R.S.D. < 7%) and accuracy (bias < or = 8%) for the tested concentration range 0.5-5 nM proved to be well within accepted limits. No significant differences in metabolic rates were detected using substrates from cold (non-labelling) chemistry syntheses and PET labelling batches, indicating the validity of using substrates from the latter source. A para-methoxy-benzamide analogue (MeO-WAY) displayed a significantly lower rate of metabolism compared to WAY-100635, whereas a para-iodo-benzamide analogue was more susceptible to metabolic transformation. LC-MS/MS Analysis of formed metabolites from WAY-100635 and MeO-WAY suggested similar metabolic pathways, with hydroxylation, demethylation and dearylation reactions. The main metabolic route in humans, amide hydrolysis, was not observed with the rat liver microsome assay.
Collapse
Affiliation(s)
- M Lavén
- Department of Analytical Chemistry, Institute of Chemistry, Uppsala University, Box 599, 751 24 Uppsala, Sweden
| | | | | | | |
Collapse
|
9
|
Lang L, Jagoda E, Ma Y, Sassaman MB, Eckelman WC. Synthesis and in vivo biodistribution of F-18 labeled 3-cis-, 3-trans-, 4-cis-, and 4-trans-fluorocyclohexane derivatives of WAY 100635. Bioorg Med Chem 2006; 14:3737-48. [PMID: 16488611 DOI: 10.1016/j.bmc.2006.01.064] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2005] [Accepted: 01/13/2006] [Indexed: 11/15/2022]
Abstract
Radioligands that are specific for the serotonin 5-HT(1A) receptor will be useful in characterizing the physiological action of this receptor subtype. With radioligands of varying pharmacokinetic properties, investigators can measure not only receptor density, but also the effect of endogenous serotonin concentration. To this end, three additional fluorinated analogs of WAY 100635 were prepared and evaluated as 5-HT(1A) receptor ligands of varying pharmacokinetic properties based on our previous studies. These four compounds are cis-4-fluoro-, trans-4-fluoro-, cis-3-fluoro-, and trans-3-fluoro-N-{2-[4-(2-methoxyphenyl)piperazin-1-yl]ethyl}-N-(pyridin-2-yl)cyclohexanecarboxamides (FCWAYs). All four compounds were characterized and radiolabeled with fluorine-18, a 109.7 min half-life radionuclide used in positron emission tomography. We then determined in vitro inhibition constants at the 5-HT(1A) receptor; in vitro metabolic profile, using rat hepatocytes and liquid chromatography/mass spectroscopy (LC/MS); and the rate of defluorination and hippocampus to cerebellum ratio ex vivo. This led to the conclusion that high affinity 4-trans-F-18 FCWAY had the best properties for measuring receptor density given its high hippocampus to cerebellum ratio and 3-cis-F-18 FCWAY had the best properties for measuring dynamic change in receptors, with lower affinity and faster pharmacokinetics.
Collapse
Affiliation(s)
- Lixin Lang
- PET Department, Warren Grant Magnuson Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA.
| | | | | | | | | |
Collapse
|
10
|
Ryu EK, Choe YS, Kim DH, Ko BH, Choi Y, Lee KH, Kim BT. In vitro metabolism studies of 18F-labeled 1-phenylpiperazine using mouse liver S9 fraction. Nucl Med Biol 2006; 33:165-72. [PMID: 16546670 DOI: 10.1016/j.nucmedbio.2005.12.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2005] [Revised: 11/26/2005] [Accepted: 12/04/2005] [Indexed: 11/17/2022]
Abstract
The in vitro metabolism of 1-(4-[(18)F]fluoromethylbenzyl)-4-phenylpiperazine ([(18)F]1) and 1-(4-[(18)F]fluorobenzyl)-4-phenylpiperazine ([(18)F]2) was investigated using mouse liver S9 fraction. Results were compared to those of in vivo metabolism using mouse blood and bone and to in vitro metabolism using mouse liver microsomes. Defluorination was the main metabolic pathway for [(18)F]1 in vitro and in vivo. Based on TLC, HPLC and LC-MS data, [(18)F]fluoride ion and less polar radioactive metabolites derived from aromatic ring oxidation were detected in vitro, and the latter metabolites were rapidly converted into the former with time, whereas only the [(18)F]fluoride ion was detected in vivo. Similarly, the in vitro metabolism of [(18)F]2 using either S9 fraction or microsomes showed the same pattern as the in vivo method using blood; however, the radioactive metabolites derived from aromatic ring oxidation were not detected in vivo. These results demonstrate that liver S9 fraction can be widely used to investigate the intermediate radioactive metabolites and to predict the in vivo metabolism of radiotracers.
Collapse
Affiliation(s)
- Eun Kyoung Ryu
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 135-710, South Korea
| | | | | | | | | | | | | |
Collapse
|
11
|
Giovacchini G, Lang L, Ma Y, Herscovitch P, Eckelman WC, Carson RE. Differential effects of paroxetine on raphe and cortical 5-HT1A binding: a PET study in monkeys. Neuroimage 2005; 28:238-48. [PMID: 15993625 DOI: 10.1016/j.neuroimage.2005.05.042] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2005] [Revised: 05/03/2005] [Accepted: 05/19/2005] [Indexed: 10/25/2022] Open
Abstract
Positron emission tomography (PET) ligands that are sensitive to transient changes in serotonin (5-HT) concentration are desirable for studies of neuropsychiatric diseases. Few studies, however, have sought to demonstrate that variations in 5-HT concentration can be closely tracked with available serotonergic ligands. Microdialysis studies in rats have shown a maximal increase in 5-HT concentration in raphe nuclei after systemic infusion of selective serotonergic re-uptake inhibitors (SSRIs). We performed PET scans with [(18)F]FPWAY, an intermediate-affinity antagonist of 5-HT(1A) receptors, in 4 anesthetized rhesus monkeys in control studies and after systemic paroxetine administration (5 mg/kg, i.v.). In addition, a paired [(11)C]DASB study revealed that this paroxetine regimen produced an occupancy of 54-83% of the serotonin transporters. According to the conventional receptor competition model, increased 5-HT concentration produces decreased binding of the radioactive ligand. Over a 3-h period following paroxetine infusion, a progressively increasing reduction (ranging from 8 +/- 6% to 27 +/- 10%) of [(18)F]FPWAY-specific binding was found in the raphe nuclei. This result is interpreted as an SSRI-induced increase in 5-HT concentration, potentially combined with reduced binding to internalized 5-HT(1A) receptors. In addition, a transient (1 h) increase in cerebral cortical binding was observed, attributed primarily to a reduction in cortical 5-HT due to the effects of raphe autoreceptor inhibition. This study is the first demonstration of the feasibility of quantifying dynamic changes in 5-HT neurotransmission in the raphe and the cortex with PET. These results lend promise to the use of these serotonergic neuroimaging techniques to study neuropsychiatric disorders.
Collapse
Affiliation(s)
- Giampiero Giovacchini
- PET Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA
| | | | | | | | | | | |
Collapse
|
12
|
Marchais-Oberwinkler S, Nowicki B, Pike VW, Halldin C, Sandell J, Chou YH, Gulyas B, Brennum LT, Farde L, Wikström HV. N-Oxide analogs of WAY-100635: new high affinity 5-HT1A receptor antagonists. Bioorg Med Chem 2005; 13:883-93. [PMID: 15653354 DOI: 10.1016/j.bmc.2004.10.033] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2003] [Accepted: 10/13/2004] [Indexed: 11/30/2022]
Abstract
WAY-100635 [N-(2-(1-(4-(2-methoxyphenyl)piperazinyl)ethyl))-N-(2-pyridinyl)cyclohexanecarboxamide] 1 and its O-desmethyl derivative DWAY 2 are well-known high affinity 5-HT(1A) receptor antagonists, which when labeled with carbon-11 (beta+; t(1/2) = 20.4 min) in the carbonyl group are effective radioligands for imaging brain 5-HT(1A) receptors with positron emission tomography (PET). In a search for new 5-HT(1A) antagonists with different pharmacokinetic and metabolic properties, the pyridinyl N-oxide moiety was incorporated into analogs of 1 and 2. NOWAY 3, in which the pyridinyl ring of 1 was oxidized to the pyridinyl N-oxide, was prepared via nucleophilic substitution of 2-[4-(2-methoxyphenyl)piperazin-1-yl]ethylamine on 2-chloropyridine-N-oxide followed by acylation with cyclohexanecarbonyl chloride. 6Cl-NOWAY 4, a more lipophilic (pyridinyl-6)-chloro derivative of 3, was prepared by treating 1-(2-methoxyphenyl)-4-(2-(2-(6-bromo)aminopyridinyl-N-oxide)ethyl)piperazine with cyclohexanecarbonyl chloride for acylation and concomitant chloro for bromo substitution. NEWWAY 5, in which the 2-hydroxy-phenyl group of 2 is replaced with a 2-pyridinyl N-oxide group with the intention of mimicking the topology of 2, was prepared in five steps from 2-(chloroacetylamino)pyridine. N-Oxides 3-5 were found to be high affinity antagonists at 5-HT(1A) receptors, with 3 having the highest affinity and a Ki value (0.22 nM) comparable to that of 1 (0.17 nM). By calculation the lipophilicity of 3 (LogP = 1.87) is lower than that of 1 by 1.25 LogP units while TLC and reverse phase HPLC indicate that 3 has slightly lower lipophilicity than 1. On the basis of these encouraging findings, the N-oxide 3 was selected for labeling with carbon-11 in its carbonyl group and for evaluation as a radioligand with PET. After intravenous injection of [carbonyl-11C]3 into cynomolgus monkey there was very low uptake of radioactivity into brain and no PET image of brain 5-HT(1A) receptors was obtained. Either 3 inadequately penetrates the blood-brain barrier or it is excluded from brain by an active efflux mechanism. Rapid deacylation of 3 was not apparent in vivo; in cynomolgus monkey plasma radioactive metabolites of [carbonyl-11C]3 appeared less rapidly than from the radioligands [carbonyl-11C]1 and [carbonyl-11C]2, which are known to be primarily metabolized by deacylation. Ligand 3 may have value as a new pharmacological tool, but not as a radioligand for brain imaging.
Collapse
Affiliation(s)
- Sandrine Marchais-Oberwinkler
- Department of Medicinal Chemistry, University Center for Pharmacy, University of Groningen, Antonius Deusinglaan 1, NL-9713 AV Groningen, The Netherlands.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Scott Mason N, Mathis CA. Positron Emission Tomography Agents for Central Nervous System Drug Development Applications. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 2005. [DOI: 10.1016/s0065-7743(05)40004-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
|
14
|
Ma Y, Lang L, Kiesewetter DO, Vuong BK, Channing M, Ito Y, Eckelman WC. Purification of the precursor for the automated radiosynthesis of []FCWAY by counter-current chromatography. J Chromatogr A 2004; 1034:149-53. [PMID: 15116924 DOI: 10.1016/j.chroma.2004.01.059] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Radiolabeled FCWAY (N-(2-[4-(2-methoxyphenyl)piperazino])-N-(2-pyridinyl) trans-4-fluorocyclohexanecarboxamide) was prepared for human positron emission tomography (PET) studies by a simple one-step radiosynthesis. The LC-MS analysis of the products indicated that it contained impurities which may interfere with FCWAY uptake of 5-HT1A receptors and that these impurities were derived from an impurity originally present in the precursor preparation. Since preparative HPLC failed to resolve one of the impurities from the precursor, preparative-scale high-speed counter-current chromatography (HSCCC) was used for purification of this FCWAY precursor. A suitable two-phase solvent system composed of cyclohexane-ethyl acetate-methanol-water at a volume ratio of 1:1:1:1 or 4:5:4:5 was selected based on the partition coefficients of the precursor and impurity as determined by a LC-MS method. Using the second solvent ratio of 4:5:4:5 with the organic phase as a mobile phase, a 2.57 g amount of precursor preparation was successfully purified yielding 2.2 g of the pure precursor by a single run.
Collapse
Affiliation(s)
- Ying Ma
- PET Department, Warren Grant Magnuson Clinical Center, National Institutes of Health, Bldg 10, Rm 1C401, 10 Center Drive MSC 1180, Bethesda, MD 20892, USA.
| | | | | | | | | | | | | |
Collapse
|
15
|
Eckelman WC. The use of gene-manipulated mice in the validation of receptor binding radiotracer. Nucl Med Biol 2003; 30:851-60. [PMID: 14698789 DOI: 10.1016/s0969-8051(03)00123-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- William C Eckelman
- PET Department, Warren G. Magnuson Clinical Center, Bethesda, MD 20892, USA.
| |
Collapse
|
16
|
Karramkam M, Hinnen F, Berrehouma M, Hlavacek C, Vaufrey F, Halldin C, McCarron JA, Pike VW, Dollé F. Synthesis of a [6-pyridinyl-18F]-labelled fluoro derivative of WAY-100635 as a candidate radioligand for brain 5-HT1A receptor imaging with PET. Bioorg Med Chem 2003; 11:2769-82. [PMID: 12788351 DOI: 10.1016/s0968-0896(03)00225-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In recent years, considerable effort has been spent on the design, synthesis and pharmacological characterization of radiofluorinated derivatives of the 5-HT(1A) receptor antagonist, WAY-100635, for the in vivo study of these receptors in human brain with PET. (Pyridinyl-6)-fluoro- and (pyridinyl-5)-fluoro-analogues of WAY-100635 (6-fluoro and 5-fluoro-WAY-100635, 5a/6a) were synthesized as well as the corresponding chloro-, bromo- and nitro-derivatives as precursors for labelling (5b-d and 6b-d). Comparative radiolabelling of these precursors with fluorine-18 (positron-emitting isotope, 109.8 min half-life) clearly demonstrated that only ortho-fluorination in this pyridine series, and not meta-fluorination, is of interest for the preparation of a radioligand by nucleophilic heteroaromatic substitution. 6-[(18)F]Fluoro-WAY-100635 ([(18)F]5a) can be efficiently synthesized in one step, either from the corresponding 6-bromo precursor (using conventional heating at 145 degrees C for 10 min) or from the corresponding 6-nitro precursor (using microwave activation at 100 W for 1 min). Typically, 15-25 mCi (0.55-0.92 GBq) of 6-[(18)F]fluoro-WAY-100635 ([(18)F]5a, 1-2 Ci/micromol or 37-72 GBq/micromol) were obtained in 50-70 min starting from a 100 mCi (3.7 GBq) aliquot of a batch of cyclotron-produced [(18)F]fluoride. This (18)F-labelled radioligand is now being evaluated in PET studies.
Collapse
Affiliation(s)
- Mylène Karramkam
- Service Hospitalier Frédéric Joliot, Département de Recherche Médicale, CEA, 4 place du Général Leclerc, F-91401 Orsay, France
| | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Ma Y, Kiesewetter DO, Lang L, Der M, Huang B, Carson RE, Eckelman WC. Determination of [18F]FCWAY, [18F]FP-TZTP, and their metabolites in plasma using rapid and efficient liquid-liquid and solid phase extractions. Nucl Med Biol 2003; 30:233-40. [PMID: 12745014 DOI: 10.1016/s0969-8051(02)00452-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Liquid-liquid and solid phase extraction methods were developed for the accurate and rapid quantitation of radioactive components in human plasma following injection of two PET ligands. A solid phase extraction (SPE) method was developed for the determination of the 5HT(1A) receptor ligand [N-[2-[4-(2-methoxyphenyl) piperazino]ethyl]-N-(2-pyridinyl) trans-4-[(18)F]fluorocyclohexanecarboxamide (FCWAY), and its acidic metabolite, 4-[(18)F]fluorocyclohexane carboxylic acid (FC). In both cases, the extraction method was much faster and easier to use, yet provided results comparable to HPLC and TLC methods. In addition, an easy to perform two-step liquid-liquid extraction was developed for quantitation of 3-(3-((3-[(18)F]fluoropropyl)thio)-1,2,5-thiadiazol-4-yl)-1,2,5,6-tetrahydro-1-methylpyridine ([(18)F]FP-TZTP), a selective M2 muscarinic agonist.
Collapse
Affiliation(s)
- Ying Ma
- PET Department, The Warren G Magnuson Clinical Center, National Institutes of Health, Bethesda, MD, USA.
| | | | | | | | | | | | | |
Collapse
|
18
|
Ma Y, Lang L, Kiesewetter DO, Eckelman WC. Liquid chromatography-tandem mass spectrometry identification of metabolites of three phenylcarboxyl derivatives of the 5-HT(1A) antagonist, N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridyl) trans-4-fluorocyclohexanecarboxamide (FCWAY), produced by human and rat hepatocytes. J Chromatogr B Analyt Technol Biomed Life Sci 2002; 780:99-110. [PMID: 12383485 DOI: 10.1016/s1570-0232(02)00434-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We have previously described fluorine-18 radiolabeled FCWAY [N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridyl) trans-4-fluorocyclohexanecarboxamide] as a high affinity ligand for imaging the 5-HT(1A) receptor in vivo. In a search for radiopharmaceuticals with unique imaging applications using positron emission tomography (PET), we have also developed three new phenylcarboxamide analogues of FCWAY. Two of these analogues were generated by replacing the fluorocyclohexane carboxylic acid with fluorobenzoic acid (FBWAY) or with 3-methyl-4-fluorobenzoic acid (MeFBWAY). The final analogue was generated by replacing the pyridyl group with a pyrimidyl group and the fluorocyclohexane carboxylate with fluorobenzoic acid (FPWAY). We evaluated the metabolic profile of these compounds using either human or rat hepatocytes to produce metabolites and LC-MS/MS to identify these metabolites. We also compared the metabolic rate of these compounds in human or rat hepatocytes. These in vitro metabolism studies indicate that hydrolysis of the amide linkage was the major metabolic pathway for FPWAY and FBWAY in human hepatocytes, whereas aromatic oxidation is the major metabolic pathway for MeFBWAY. The comparative metabolic rate in human hepatocytes was FPWAY>FBWAY>MeFBWAY. In rat hepatocytes, aromatic oxidation was the major metabolic pathway for all three analogs and the rate of this process was similar for all of the analogues. These in vitro metabolic studies demonstrated species differences prior to the acquisition and interpretation of in vivo results.
Collapse
Affiliation(s)
- Ying Ma
- PET Department, Warren G Magnuson Clinical Center, National Institutes of Health, Bldg 10 Rm 1C401, 10 Center Drive MSC 1180, Bethesda, MD 20892, USA.
| | | | | | | |
Collapse
|
19
|
Chapter 7: Biokinetics. Altern Lab Anim 2002. [DOI: 10.1177/026119290203001s07] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
20
|
Anderson CJ. Metabolism of radiometal-labeled proteins and peptides: what are the real radiopharmaceuticals in vivo? Cancer Biother Radiopharm 2001; 16:451-5. [PMID: 11789022 DOI: 10.1089/10849780152752056] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
|
21
|
Current literature in mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2001; 36:1076-1082. [PMID: 11599087 DOI: 10.1002/jms.96] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
|